The Islamic, Muslim, or Hijri calendar is a lunar calendar consisting of 12 lunar months in a year of 354 or 355 days. It is used to determine the proper days of Islamic holidays and rituals, such as the annual period of fasting and the proper time for the pilgrimage to Mecca; the civil calendar of all countries where the religion is predominantly Muslim is the Gregorian calendar. Notable exceptions to this rule are Afghanistan, which use the Solar Hijri calendar. Rents and similar regular commitments are paid by the civil calendar; the Islamic calendar employs the Hijri era whose epoch was established as the Islamic New Year of 622 AD/CE. During that year and his followers migrated from Mecca to Yathrib and established the first Muslim community, an event commemorated as the Hijra. In the West, dates in this era are denoted AH in parallel with the Christian and Jewish eras. In Muslim countries, it is sometimes denoted as H from its Arabic form. In English, years prior to the Hijra are reckoned as BH.
The current Islamic year is 1440 AH. In the Gregorian calendar, 1440 AH runs from 11 September 2018 to 30 August 2019. For central Arabia Mecca, there is a lack of epigraphical evidence but details are found in the writings of Muslim authors of the Abbasid era. Inscriptions of the ancient South Arabian calendars reveal the use of a number of local calendars. At least some of these South Arabian calendars followed the lunisolar system. Both al-Biruni and al-Mas'udi suggest that the ancient Arabs used the same month names as the Muslims, though they record other month names used by the pre-Islamic Arabs; the Islamic tradition is unanimous in stating that Arabs of Tihamah and Najd distinguished between two types of months and forbidden months. The forbidden months were four months during which fighting is forbidden, listed as Rajab and the three months around the pilgrimage season, Dhu al-Qa‘dah, Dhu al-Hijjah, Muharram. Information about the forbidden months is found in the writings of Procopius, where he describes an armistice with the Eastern Arabs of the Lakhmid al-Mundhir which happened in the summer of 541 AD/CE.
However, Muslim historians do not link these months to a particular season. The Qur'an links the four forbidden months with Nasī’, a word that means "postponement". According to Muslim tradition, the decision of postponement was administered by the tribe of Kinanah, by a man known as the al-Qalammas of Kinanah and his descendants. Different interpretations of the concept of Nasī’ have been proposed; some scholars, both Muslim and Western, maintain that the pre-Islamic calendar used in central Arabia was a purely lunar calendar similar to the modern Islamic calendar. According to this view, Nasī’ is related to the pre-Islamic practices of the Meccan Arabs, where they would alter the distribution of the forbidden months within a given year without implying a calendar manipulation; this interpretation is supported by Arab historians and lexicographers, like Ibn Hisham, Ibn Manzur, the corpus of Qur'anic exegesis. This is corroborated by an early Sabaic inscription, where a religious ritual was "postponed" due to war.
According to the context of this inscription, the verb ns'’ has nothing to do with intercalation, but only with moving religious events within the calendar itself. The similarity between the religious concept of this ancient inscription and the Qur'an suggests that non-calendaring postponement is the Qur'anic meaning of Nasī’; the Encyclopaedia of Islam concludes "The Arabic system of can only have been intended to move the Hajj and the fairs associated with it in the vicinity of Mecca to a suitable season of the year. It was not intended to establish a fixed calendar to be observed." The term "fixed calendar" is understood to refer to the non-intercalated calendar. Others concur that it was a lunar calendar, but suggest that about 200 years before the Hijra it was transformed into a lunisolar calendar containing an intercalary month added from time to time to keep the pilgrimage within the season of the year when merchandise was most abundant; this interpretation was first proposed by the medieval Muslim astrologer and astronomer Abu Ma'shar al-Balkhi, by al-Biruni, al-Mas'udi, some western scholars.
This interpretation considers Nasī’ to be a synonym to the Arabic word for "intercalation". The Arabs, according to one explanation mentioned by Abu Ma'shar, learned of this type of intercalation from the Jews; the Jewish Nasi was the official. Some sources say that the Arabs followed the Jewish practice and intercalated seven months over nineteen years, or else that they intercalated nine months over 24 years. Postponement of one ritual in a particular circumstance does not imply alteration of the sequence of months, scholars agree that this did not happen. Al-Biruni says this did not happen, the festivals were kept within their season by intercalation every second or third year of a month between Dhu al-Hijjah and Muharram, he says that, in terms of the fixed calendar, not introduced until 10 AH, the first intercalation was, for example, of a month between Dhu al-Hijjah and Muharram, the second of a month between Muharram and Safar, the third of a month between Safar and Rabi'I, so on. The intercalations were arranged.
The notice of interca
The 16th century begins with the Julian year 1501 and ends with either the Julian or the Gregorian year 1600. The 16th century is regarded by historians as the century. During the 16th century and Portugal explored the world's seas and opened worldwide oceanic trade routes. Large parts of the New World became Spanish and Portuguese colonies, while the Portuguese became the masters of Asia's and Africa's Indian Ocean trade, the Spanish opened trade across the Pacific Ocean, linking the Americas with Asia; this era of colonialism established mercantilism as the leading school of economic thought, where the economic system was viewed as a zero-sum game in which any gain by one party required a loss by another. The mercantilist doctrine encouraged the many intra-European wars of the period and arguably fueled European expansion and imperialism throughout the world until the 19th century or early 20th century. In Europe, the Protestant Reformation gave a major blow to the authority of the papacy and the Roman Catholic Church.
European politics became dominated by religious conflicts, with the groundwork for the epochal Thirty Years' War being laid towards the end of the century. In Italy, Luca Pacioli published the first work on accounting and Galileo Galilei made the first thermometer. In England, the Italian Alberico Gentili wrote the first book on public international law and divided secularism from canon law and Roman Catholic theology. In the Middle East, the Ottoman Empire continued to expand, with the Sultan taking the title of Caliph, while dealing with a resurgent Persia. Iran and Iraq were caught by major popularity of the Shiite sect of Islam under the rule of the Safavid dynasty of warrior-mystics, providing grounds for a Persia independent of the majority-Sunni Muslim world. China evacuated the coastal areas, because of Japanese piracy. Japan was suffering a severe civil war at the time, known as the Sengoku period. Elsewhere in Asia, Mughal Emperor Akbar extended the power of the Mughal Empire to cover most of the southern lands of the continent.
His rule influenced arts and culture in the region. Copernicus proposed the heliocentric universe, met with strong resistance, Tycho Brahe refuted the theory of celestial spheres through observational measurement of the 1572 appearance of a Milky Way supernova; these events directly challenged the long-held notion of an immutable universe supported by Ptolemy and Aristotle, led to major revolutions in astronomy and science. Polybius' "The Histories" translated into Italian, English and French. Mississippian culture disappears. Medallion rug, variant Star Ushak style, Anatolia, is made, it is now kept at The Saint Louis Art Museum. 1500: Charles V, Holy Roman Emperor and King of Spain was born. 1500: Guru Nanak the beginning and spreading of the 5th largest religion in the world Sikhism. 1500: Spanish navigator Vicente Yáñez Pinzón encounters Brazil but is prevented from claiming it by the Treaty of Tordesillas. 1500: Portuguese navigator Pedro Álvares Cabral claims Brazil for Portugal. 1500: The Ottoman fleet of Kemal Reis defeats the Venetians at the Second Battle of Lepanto.
1501: Michelangelo returns to his native Florence to begin work on the statue David. 1501: Safavid dynasty reunified Iran and ruled over it until 1736. Safavids adopt a Shia branch of Islam. 1502: First reported African slaves in The New World 1503: Foundation of the Sultanate of Sennar by Amara Dunqas, in what is modern Sudan 1503: Spain defeats France at the Battle of Cerignola. Considered to be the first battle in history won by gunpowder small arms. 1503: Leonardo da Vinci begins painting the Mona Lisa and completes it three years later. 1503: Nostradamus was born on either December 14, or December 21. 1504: A period of drought, with famine in all of Spain. 1504: Death of Isabella I of Castile, Joanna of Castille became the Queen. 1505: Zhengde Emperor ascended the throne of Ming Dynasty. 1505: Martin Luther enters St. Augustine's Monastery at Erfurt, Germany, on 17 July and begins his journey to instigating the Reformation. 1505: King Sultan Trenggono built the first Muslim kingdom in Java, called Demak, in Indonesia's of a homelessness of a.
Many other small kingdoms were established in other islands to fight against Portuguese. Each kingdom introduced local language as a way of unity. 1506: Leonardo da Vinci completes the Mona Lisa. 1506: King Afonso I of Kongo wins the battle of Mbanza Kongo, resulting in Catholicism becoming Kongo's state religion. 1506: At least two thousand converted Jews are massacred in a Lisbon riot, Portugal. 1506: Christopher Columbus dies in Valladolid, Spain. 1506: Poland is invaded by Tatars from the Crimean Khanate. 1507: The first recorded epidemic of smallpox in the New World on the island of Hispaniola. It devastates the native Taíno population. 1507: Afonso de Albuquerque conquered Hormuz and Muscat, among other bases in the Persian Gulf, taking control of the region at the entrance of the Gulf. 1508–1512: Michelangelo paints the Sistine Chapel ceiling. 1509: The Battle of Diu marks the beginning of Portuguese dominance of the Spice trade and the Indian Ocean. 1509: The Portuguese king sends Diogo Lopes de Sequeira to find Malacca, the eastern terminus of Asian trade.
After receiving Sequeira, Sultan Mahmud Syah captures and/or kills several of his men and attempts an assault on the four Portuguese ships, which escape. The Javanese fleet is destroyed in Malacca.. 1509–10: The'great plague' in various parts of Tudor England. 1511: Afonso de Albuquerque of Portugal conquers Malacca, the capital of the Sultanate of Malacca in present-day Malaysia. 1512: Copernicus writes Commentar
The Buddhist calendar is a set of lunisolar calendars used in mainland Southeast Asian countries of Cambodia, Laos and Thailand as well as in Sri Lanka and Chinese populations of Malaysia and Singapore for religious or official occasions. While the calendars share a common lineage, they have minor but important variations such as intercalation schedules, month names and numbering, use of cycles, etc. In Thailand, the name Buddhist Era is a year numbering system shared by the traditional Thai lunisolar calendar and by the Thai solar calendar; the Southeast Asian lunisolar calendars are based on an older version of the Hindu calendar, which uses the sidereal year as the solar year. One major difference is that the Southeast Asian systems, unlike their Indian cousins, do not use apparent reckoning to stay in sync with the sidereal year. Instead, they employ their versions of the Metonic cycle. However, since the Metonic cycle is not accurate for sidereal years, the Southeast Asian calendar is drifting out of sync with the sidereal one day every 100 years.
Yet no coordinated structural reforms of the lunisolar calendar have been undertaken. Today, the traditional Buddhist lunisolar calendar is used for Theravada Buddhist festivals, no longer has the official calendar status anywhere; the Thai Buddhist Era, a renumbered Gregorian calendar, is the official calendar in Thailand. The calculation methodology of the current versions of Southeast Asian Buddhist calendars is based on that of the Burmese calendar, in use in various Southeast Asian kingdoms down to the 19th century under the names of Chula Sakarat and Jolak Sakaraj; the Burmese calendar in turn was based on the "original" Surya Siddhanta system of ancient India. One key difference with Indian systems is that the Burmese system has followed a variation of the Metonic cycle, it is unclear from where, how the Metonic system was introduced. The Burmese system, indeed the Southeast Asian systems, thus use a "strange" combination of sidereal years from Indian calendar in combination with the Metonic cycle better for tropical years.
In all Theravada traditions, the calendar's epochal year 0 date was the day in which the Buddha attained parinibbāna. However, not all traditions agree on when it took place. In Burmese Buddhist tradition, it was 13 May 544 BCE, but in Thailand, it was 11 March 545 BCE, the date which the current Thai lunisolar and solar calendars use as the epochal date. Yet, the Thai calendars for some reason have fixed the difference between their Buddhist Era numbering and the Christian/Common Era numbering at 543, which points to an epochal year of 544 BCE, not 545 BCE. In Myanmar, the difference between BE and CE can be 543 or 544 for CE dates, 544 or 543 for BCE dates, depending on the month of the Buddhist Era. In Sri Lanka, the difference between BE and CE is 544; the calendar recognizes two types of months: sidereal month. The Synodic months are used to compose the years while the 27 lunar sidereal days, alongside the 12 signs of the zodiac, are used for astrological calculations; the days of the month are counted in two halves and waning.
The 15th of the waxing is the civil full moon day. The civil new moon day is the last day of the month; because of the inaccuracy of the calendrical calculation systems, the mean and real New Moons coincide. The mean New Moon precedes the real New Moon; as the Synodic lunar month is 29.5 days, the calendar uses alternating months of 29 and 30 days. Various regional versions of Chula Sakarat/Burmese calendar existed across various regions of mainland Southeast Asia. Unlike Burmese systems, Lan Na, Lan Xang and Sukhothai systems refer to the months by numbers, not by names; this means reading ancient texts and inscriptions in Thailand requires constant vigilance, not just in making sure one is operating for the correct region, but for variations within regions itself when incursions cause a variation in practice. However, Cambodian month system, which begins with Margasirsa as the first month, demonstrated by the names and numbers; the Buddhist calendar is a lunisolar calendar in which the months are based on lunar months and years are based on solar years.
One of its primary objectives is to synchronize the lunar part with the solar part. The lunar months twelve of them, consist alternately of 29 days and 30 days, such that a normal lunar year will contain 354 days, as opposed to the solar year of ~365.25 days. Therefore, some form of addition to the lunar year is necessary; the overall basis for it is provided by cycles of 57 years. Eleven extra days are inserted in every 57 years, seven extra months of 30 days are inserted in every 19 years; this provides 20819 complete days to both calendars. This 57-year cycle would provide a mean year of about 365.2456 days and a mean month of about 29.530496 days, if not corrected. As such, the calendar adds an intercalary month in leap years and sometimes an intercalary day in great leap years; the intercalary month not only corrects the length of the year but corrects the accumulating error of the month to extent of half a day. The average length of the month is further corrected by adding a day to Nayon
Kali Yuga in Hinduism is the last of the four stages the world goes through as part of a'cycle of yugas' described in the Sanskrit scriptures. The other ages are called Satya Yuga, Treta Yuga, Dvapara Yuga. Kali Yuga is associated with the demon Kali; the "Kali" of Kali Yuga means "strife", "discord", "quarrel" or "contention". According to Puranic sources, Krishna's departure marks the end of Dvapara Yuga and the start of Kali Yuga, dated to 17/18 February 3102 BCE. According to the Surya Siddhanta, Kali Yuga began at midnight on 18 February 3102 BCE; this is considered the date on which Lord Krishna left the earth to return to Vaikuntha. This information is placed at the temple of the place of this incident. According to the astronomer and mathematician Aryabhatta the Kali Yuga started in 3102 BCE, he finished his book "Aryabhattiya" in 499 CE, in which he gives the exact year of the beginning of Kali Yuga. He writes that he wrote the book in the "year 3600 of the Kali Age" at the age of 23; as it was the 3600th year of the Kali Age when he was 23 years old, given that Aryabhatta was born in 476 CE, the beginning of the Kali Yuga would come to 3102 BCE.
According to KD Abhyankar, the starting point of Kali Yuga is an rare planetary alignment, depicted in the Mohenjo-Daro seals. Going by this alignment the year 3102 BCE is off; the actual date for this alignment is 7 February of 3104 BCE. There is sufficient proof to believe that Vrdhha Garga knew of precession at least by 500 BCE. Garga had calculated the rate of precession to within 30 % of; the common belief until Swami Sri Yukteswar Giri had analyzed the dating of the Yuga cycles was that the Kali Yuga would last for 432,000 years after the end of the Dwapara Yuga. This originated during the puranic times when the famous astronomer Aryabhatta recalculated the timeline by artificially inflating the traditional 12,000 year figure with a multiplication of 360, represented as the number of "human years" that make up a single "divine year"; this was a purposeful miscalculation due to conflicts with one of the preeminent astronomer of the time Brahmagupta. However, both the Mahabharata and the Manu Smriti have the original value of 12,000 years for one half of the Yuga cycle.
Contemporary analysis of historical data from the last 11 millennia matches with the indigenous Saptarishi Calendar. The length of the transitional periods between each Yuga is unclear, can only be estimated based on historical data of past cataclysmic events. Using a 300 year period for transitions, Kali Yuga has either ended in the past 100 to 200 years, or is to end soon sometime in the next 100 years. Other authors, such as the revered Hindu guru Swami Sri Yukteswar in his book The Holy Science, as well as the influential Yogi Paramhansa Yogananda, believe that the Kali Yuga has ended, that we are now in an ascending Dvapara Yuga; this calculation is supported by modern day spiritual masters such as Sadhguru Jaggi Vasudev. Hindus believe that human civilization degenerates spiritually during the Kali Yuga, referred to as the Dark Age because in it people are as far away as possible from God. Hinduism symbolically represents morality as an Indian bull. Common attributes and consequences are spiritual bankruptcy, mindless hedonism, breakdown of all social structure and materialism, unrestricted egotism and maladies of mind and body.
In Satya Yuga, the first stage of development, the bull has four legs, but in each age morality is reduced by one quarter. By the age of Kali, morality is reduced to only a quarter of that of the golden age, so that the bull of Dharma has only one leg; the Mahabharata War and the decimation of Kauravas thus happened at the "Yuga-Sandhi", the point of transition from one yuga to another. The scriptures mention Sage Narada to have momentarily intercepted the demon Kali on his way to the Earth when Duryodhana was about to be born in order to make him an embodiment of arishadvargas and adharma in preparation of the era of decay in values and the consequent havoc. A discourse by Markandeya in the Mahabharata identifies some of the attributes of Kali Yuga. In relation to rulers, it lists: Rulers will become unreasonable: they will levy taxes unfairly. Rulers will no longer see it as their duty to promote spirituality, or to protect their subjects: they will become a danger to the world. People will start seeking countries where wheat and barley form the staple food source.
"At the end of Kali-yuga, when there exist no topics on the subject of God at the residences of so-called saints and respectable gentlemen of the three higher varnas and when nothing is known of the techniques of sacrifice by word, at that time the Lord will appear as the supreme chastiser." (Srimad-Bhagavatam With regard to human relationships, Markandeya's discourse says: Avarice and wrath will be common. Humans will display animosity towards each other. Ignorance of dharma will occur. People will see nothing wrong in that. Lust will be viewed as acceptable and sexual intercourse will be seen as the central requirement of life. Sin will increase exponentially, while virtue will cease to flourish. People will become addicted to intoxicating drugs. Gurus will no longer be respected and their students will attempt
Hōtoku was a Japanese era name after Bun'an and before Kyotoku. This period spanned the years from July 1449 through July 1452; the reigning emperor was Go-Hanazono-tennō. 1449 Hōtoku gannen: The era name was changed to mark an event or a number of events. The previous era ended and a new one commenced in 1449 The first year of Hotoku began on the 28th day of the 7th month. On the 10th day, the era name would still have been Bun'an 6. May 8, 1449: Shōgun Yoshinari is honored by the emperor with the gift of a sword. 1451: A delegation from the Ryukyu Islands arrives for the first time in Heian-kyō. Mention of this diplomatic event is among the first of its type to be published in the West in an 1832 French version of Sangoku Tsūran Zusetsu by Hayashi Shihei. 1451: Sogun Yoshihori causes a letter to be sent to the Emperor of China. Appreciation for the waka poetry of Shōtetsu and Shinkei was noteworthy during this era. Hayashi, Shihei.. Sangoku Tsūran Zusetsu. Edo: Manuscript. OCLC 44014900 Klaproth, Julius..
San kokf tsou ran to sets, ou Aperçu général des trois royaumes. Paris: Royal Asiatic Society, Oriental Translation Fund of Great Britain and Ireland. OCLC 2563166. Japan Encyclopedia. Cambridge: Harvard University Press. ISBN 978-0-674-01753-5. Nihon Odai Ichiran. Paris: Royal Asiatic Society, Oriental Translation Fund of Great Britain and Ireland. OCLC 5850691. National Diet Library, "The Japanese Calendar" -- historical overview plus illustrative images from library's collection
Indian national calendar
The Indian national calendar, sometimes called the Shalivahana Shaka calendar. It is used, alongside the Gregorian calendar, by The Gazette of India, in news broadcasts by All India Radio and in calendars and communications issued by the Government of India; the Saka calendar is used in Java and Bali among Indonesian Hindus. Nyepi, the "Day of Silence", is a celebration of the Saka new year in Bali. Nepal's Nepal Sambat evolved from the Saka calendar. Prior to colonization, the Philippines used to apply the Saka calendar as well as suggested by the Laguna Copperplate Inscription; the term may ambiguously refer to the Hindu calendar. The historic Shalivahana era calendar is still used, it has years. The calendar months follow the signs of the tropical zodiac rather than the sidereal zodiac used with the Hindu calendar. Chaitra has 30 days and starts on March 22, except in leap years, when it has 31 days and starts on March 21; the months in the first half of the year all have 31 days, to take into account the slower movement of the sun across the ecliptic at this time.
The names of the months are derived from older, Hindu lunisolar calendars, so variations in spelling exist, there is a possible source of confusion as to what calendar a date belongs to. Years are counted in the Saka era. To determine leap years, add 78 to the Saka year – if the result is a leap year in the Gregorian calendar the Saka year is a leap year as well, its structure is just like the Persian calendar. Senior Indian Astrophysicist Meghnad Saha was the head of the Calendar Reform Committee under the aegis of the Council of Scientific and Industrial Research. Other members of the Committee were: A. C. Banerjee, K. K. Daftari, J. S. Karandikar, Gorakh Prasad, R. V. Vaidya and N. C. Lahiri, it was Saha's effort. The task before the Committee was to prepare an accurate calendar based on scientific study, which could be adopted uniformly throughout India, it was a mammoth task. The Committee had to undertake a detailed study of different calendars prevalent in different parts of the country. There were thirty different calendars.
The task was further complicated by the fact that religion and local sentiments were integral to those calendars. India's first prime minister, Jawaharlal Nehru, in his preface to the Report of the Committee, published in 1955, wrote: “They represent past political divisions in the country.... Now that we have attained Independence, it is desirable that there should be a certain uniformity in the calendar for our civic and other purposes, this should be done on a scientific approach to this problem.” Usage started at 1 Chaitra 1879, Saka Era, or 22 March 1957. Report of the Calendar Reform Committee – online link. Mapping Time: The Calendar and its History by E. G. Richards, 1998, pp. 184–185. Calendars and their History Indian Calendars Positional astronomy in India Indian National Calendar abstract
The Hebrew or Jewish calendar is a lunisolar calendar used today predominantly for Jewish religious observances. It determines the dates for Jewish holidays and the appropriate public reading of Torah portions and daily Psalm readings, among many ceremonial uses. In Israel, it is used for religious purposes, provides a time frame for agriculture and is an official calendar for civil purposes, although the latter usage has been declining in favor of the Gregorian calendar; the present Hebrew calendar is the product including a Babylonian influence. Until the Tannaitic period, the calendar employed a new crescent moon, with an additional month added every two or three years to correct for the difference between twelve lunar months and the solar year; the year in which it was added was based on observation of natural agriculture-related events in ancient Israel. Through the Amoraic period and into the Geonic period, this system was displaced by the mathematical rules used today; the principles and rules were codified by Maimonides in the Mishneh Torah in the 12th century.
Maimonides' work replaced counting "years since the destruction of the Temple" with the modern creation-era Anno Mundi. The Hebrew lunar year is about eleven days shorter than the solar year and uses the 19-year Metonic cycle to bring it into line with the solar year, with the addition of an intercalary month every two or three years, for a total of seven times per 19 years. With this intercalation, the average Hebrew calendar year is longer by about 6 minutes and 40 seconds than the current mean tropical year, so that every 217 years the Hebrew calendar will fall a day behind the current mean tropical year; the era used. As with Anno Domini, the words or abbreviation for Anno Mundi for the era should properly precede the date rather than follow it. AM 5779 began at sunset on 9 September 2018 and will end at sunset on 29 September 2019; the Jewish day is of no fixed length. The Jewish day is modeled on the reference to "...there was evening and there was morning..." in the creation account in the first chapter of Genesis.
Based on the classic rabbinic interpretation of this text, a day in the rabbinic Hebrew calendar runs from sunset to the next sunset. Halachically, a day ends and a new one starts when three stars are visible in the sky; the time between true sunset and the time when the three stars are visible is known as'bein hashmashot', there are differences of opinion as to which day it falls into for some uses. This may be relevant, for example, in determining the date of birth of a child born during that gap. There is no clock in the Jewish scheme. Though the civil clock, including the one in use in Israel, incorporates local adoptions of various conventions such as time zones, standard times and daylight saving, these have no place in the Jewish scheme; the civil clock is used only as a reference point – in expressions such as: "Shabbat starts at...". The steady progression of sunset around the world and seasonal changes results in gradual civil time changes from one day to the next based on observable astronomical phenomena and not on man-made laws and conventions.
In Judaism, an hour is defined as 1/12 of the time from sunrise to sunset, so, during the winter, an hour can be much less than 60 minutes, during the summer, it can be much more than 60 minutes. This proportional hour is known as a sha'ah z'manit. A Jewish hour is divided into parts. A part is 1/18 minute; the ultimate ancestor of the helek was a small Babylonian time period called a barleycorn, itself equal to 1/72 of a Babylonian time degree. These measures are not used for everyday purposes. Instead of the international date line convention, there are varying opinions as to where the day changes. One opinion uses the antimeridian of Jerusalem. Other opinions exist as well; the weekdays proceed to Saturday, Shabbat. Since some calculations use division, a remainder of 0 signifies Saturday. While calculations of days and years are based on fixed hours equal to 1/24 of a day, the beginning of each halachic day is based on the local time of sunset; the end of the Shabbat and other Jewish holidays is based on nightfall which occurs some amount of time 42 to 72 minutes, after sunset.
According to Maimonides, nightfall occurs. By the 17th century, this had become three-second-magnitude stars; the modern definition is when the center of the sun is 7° below the geometric horizon, somewhat than civil twilight at 6°. The beginning of the daytime portion of each day is determined both by sunrise. Most halachic times are based on some combination of these four times and vary from day to day throughout the year and vary depending on location; the daytime hours are divided into Sha'oth Zemaniyoth or "Halachic hours" by taking the time between sunrise and sunset or between dawn and nightfall and dividing it into 12 equal hours. The nighttime hours are s